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86 Gianmarco Ingrosso et al.

represented by a bioerosion succession, generally beginning with the infes-
tation of bacteria and fungi, followed by other species. Bioerosion predom-
inantly affects the dead parts of the coral skeleton (Beuck and Freiwald,
2005), but in stressed corals the infestation can increase and also affect
living areas.
Some Mediterranean bioconstructions can be ephemeral and rapidly
degrade once the bioconstructors die, such as Sabellaria reefs, whereas others
remain stable for millennia, such as coralligenous formations. The rims of
L. byssoides are fairly persistent: in conditions of stable sea level they can grow
for centuries, up to 900–1000 years (Faivre et al., 2013; Verlaque, 2010).
Many large rims currently present in the Mediterranean Sea were formed
during two periods of global cooling in which the sea level was stable
(Dark Age Cold Period, AD 450–950, and during the Little Ice Age, AD
1400–1850, Faivre et al., 2013). The bioconstruction activity of L. byssoides
produces a very hard calcareous rock that is only eroded slowly, and which
maintains the integrity of the rim for a long time, so that its ecosystem
engineering function persists even when the living alga is no longer present.
Unfortunately, in the last decades, reports of deteriorated L. byssoides rims
have become increasingly frequent (Faivre et al., 2013; Laborel et al., 1993;
Verlaque, 2010) and a careful monitoring of these structures is now
urgently needed.
Coralligenous pinnacles dating back 6207 years from the Ionian Sea
(Bertolino et al., 2017b) showed a core partially made up by serpulid (Protula
sp.) remains, a feature in common with other bioherms studied in the
Southern Ionian Sea (Di Geronimo et al., 2002) and with pseudo-stalactites
found in several marine caves from the Aegean and Ionian Seas (Guido et al.,
2013; Sanfilippo et al., 2017). Moreover, the sediments trapped in the
crevices of these bioherms can host a high number of embedded siliceous
spicules that have been considered to be a good proxy for evaluating changes
of sponge biodiversity on a millennial timescale (Bertolino et al., 2013,
2017a,b).
The age of the deepest coralligenous bioherms can be traced back also to
8000 years ago (Ballesteros, 2006), whereas coralligenous platforms from
shallower waters were dated to around 6000 years ago (Bertolino et al.,
2017a). Generally speaking, these biostructures began to grow along the
Mediterranean coast when the effects of ice cap melting were still very relevant,
due to glacio–hydro–isostatic processes and tectonic uplifts (Pirazzoli, 2005)
andthesealevel wasfrom13.5to16.5m lowerthanatpresent (Sivan
et al., 2001). Under these conditions, the calcification rate was facilitated,